I think you may be referring to Romans 6:1-4 which says, “What shall we say then? Shall we continue in sin, that grace may abound? God forbid. How shall we, that are dead to sin, live any longer therein? Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.”  It is here that we are told that we are “baptized into his death”, that is, the death of the Lord Jesus Christ.

Let’s read these verses from the very accurate J.N. Darby translation.  That says, “What then shall we say? Should we continue in sin that grace may abound? Far be the thought. We who have died to sin, how shall we still live in it? Are you ignorant that we, as many as have been baptised unto Christ Jesus, have been baptised unto his death? We have been buried therefore with him by baptism unto death, in order that, even as Christ has been raised up from among the dead by the glory of the Father, so *we* also should walk in newness of life.”  Notice how this translation uses the word ‘unto’ rather than ‘into’.

The same Greek word (eis), that is translated ‘into’ in Romans 6:3 in the KJV, is translated ‘unto’ in 1 Corinthians 10:2 in the KJV.  That says, “And were all baptized unto Moses in the cloud and in the sea.”

It is faith in the finished work of the Lord Jesus Christ that causes us to be “in Christ Jesus” as we read in Romans 8:1, “There is therefore now no condemnation to them which are IN CHRIST JESUS, who walk not after the flesh, but after the Spirit.”  Along with that action, we are also baptized into the one body of Christ at the moment of salvation.  We read in 1 Corinthians 12:13, “For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit.”  Here we see it is the work of the Holy Spirit to incorporate all believers into one spiritual body…the body of Christ.

While water baptism cannot bring us ‘into’ Christ or ‘into’ His death, the significance of baptism is that it is an outward identification with a crucified, buried, and risen Lord.  Scripture plainly teaches us that, as believers on the Lord Jesus Christ, we died with Christ when He was crucified.  The Apostle Paul said in Galatians 2:20, “I AM CRUCIFIED WITH CHRIST: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.”  When God quickened Christ from the dead, He also quickened us; when He raised Him from the dead, He also raised us; and when the Lord Jesus sat down in the glory…we sat down together with Him.  Ephesians 2:4-6 tells us, “But God, who is rich in mercy, for his great love wherewith he loved us, Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;) And hath raised us up together, and made us sit together in heavenly places in Christ Jesus.”

I encourage you to read the book of Philippians which presents our position of being “in Christ Jesus.”  (Philippians 4:21).  Compare that with the book of Colossians which teaches us that “Christ is in you.” (Colossians 1:7).  (356.2)